WASHINGTON, D.C. -- The Obama administration will stand behind the new school meal nutrition guidelines because they are based on science, Agriculture Deputy Secretary Kathleen Merrigan said here Oct. 2.

"We feel very strongly our new school food (rules) are backed by science," Merrigan said in response to a question at the United Fresh Fruit and Vegetable Association public policy conference in Washington.

Noting that the meals are based on the 2010 dietary guidelines and that USDA's "My Plate" system recommends that half a meal plate should be filled with fruits and vegetables, Merrigan added, "That is where the science is and that's where this administration is at."

The new rules require more fruits and vegetables, lean meat and low-fat dairy products and less salt and sugar. In an attempt to deal with childhood obesity, the rules also specify the calorie counts of meals for elementary and high school students.

Some students have said they are hungry and Republicans have introduced bills in Congress to repeal the rule, which the Agriculture Department wrote to comply with the Healthy, Hunger-Free Kids Act. The issue has also been parodied by "The Daily Show" host Jon Stewart and on YouTube.

Merrigan acknowledged that there has been some push back.

"Change is hard for people. People are scared of change," she said. A video of kids fainting "is fun but not fact-based," she said, adding, "We are seeing great enthusiasm, not just among the kids, but among the school lunch professionals."

Merrigan also acknowledged that the National Association of State Departments of Agriculture at its September meeting in Des Moines approved a policy statement declaring opposition to the guidelines.

Introduced by Doug Goehring, the elected Republican agriculture commissioner in North Dakota, the resolution says NASDA opposes "restrictive dietary guidelines on meat protein and calories served through the national school lunch and breakfast program that do not take into consideration individual needs, especially those of physically active and growing students."

The policy statement calls the new guidelines "well-intentioned, but falling short of providing a comprehensive policy for educating students in healthy living."

Merrigan said in a previous interview that the NASDA statement was unnecessary because states have leeway in what they can serve children in order to conform to local dietary tastes.

"What happens in North Dakota and New Mexico do not have to be the same," Merrigan said. "Schools can be imaginative and work with students and school officials to figure out (the menus). There are definitely different palates."

On the issue of calories, she added, "Fear not that kids get adequate nutrition. We have done our homework."